Types of Aggregates Explained

Aggregates are essential materials in construction and landscaping, used in everything from road and driveway sub-bases to concrete, drainage and footpaths. Available in a range of types, sizes and materials, choosing the right aggregate is important for creating a stable, durable and suitable foundation for your project.

In this guide, Howarth Timber explains the different types of construction aggregate, including MOT Type 1, Type 2 and Type 3. Discover how they differ, where they are commonly used and what to consider when choosing between them, including strength, compaction and drainage.

Whether you’re planning a driveway, patio or larger construction project, understanding the different aggregate types can help you select the right material for the job.

What are aggregates?

Aggregates are rough, natural or recycled materials such as sand, gravel, crushed stone, or concrete. They’re often mixed with cement or asphalt to form products like concrete, road bases, footpaths, and drainage layers.

In the UK, there are two main types of aggregate:

• Primary aggregates – These come straight from quarries and include natural sand, gravel, and crushed stone.
• Secondary aggregates – These are made from recycled materials such as crushed concrete and are a more sustainable option.

MOT & type-based aggregates

Type 1 aggregate (also known as MOT Type 1)

Type 1 aggregate is a compact, load-bearing material made from crushed stone or concrete. It’s usually sized between 0-40 mm and is perfect for creating strong sub-bases for:

• Roads
• Driveways
• Patios

This is one of the most common and reliable aggregate types used in UK construction.

Type 2 Aggregate (MOT Type 2)

And what is type 2 aggregate? It’s a sub-base material graded from larger stones (up to 63 mm) down to fine particles. It compacts well and allows water to drain through, making it ideal for:

• Footpaths
• Walkways
• Pothole repairs
• Backfilling trenches

Type 2 aggregate is often made using recycled content, which supports sustainable building practices.

Type 3 Aggregate

Type 3 aggregate is a newer material that contains fewer fines (dusty particles). It’s designed to offer high drainage while still being strong and compactable.

This makes it ideal for:

• Sustainable Urban Drainage Systems (SuDS)
• Driveways
• Sports surfaces
• Car parks

If you're wondering what is type 3 aggregate, think of it as a heavy-duty, free-draining option for modern construction.

What Is the Difference Between Type 1 and Type 3 Aggregate?

The main difference between Type 1 and Type 3 aggregate is their balance of compaction, stability and permeability.

MOT Type 1 is a well-graded aggregate designed to compact into a strong, stable sub-base. It is commonly used beneath driveways, patios, paths and other surfaces where a firm foundation is required.

Type 3 aggregate contains fewer fine particles, allowing water to pass through more easily. It is commonly associated with applications where permeability and drainage are important, including suitable permeable paving systems and Sustainable Drainage Systems (SuDS).

Neither aggregate is automatically better than the other. The right choice depends on the requirements of your project, including the intended surface, drainage needs and ground conditions.

For example, a conventional driveway may require a compactable Type 1 sub-base, while a designed permeable paving system may specify Type 3 to allow water to drain through the structure.

Always follow the relevant project specification and check the individual aggregate product information before making your selection.

But why does it matter?

Choosing the right aggregate for your project is important for several reasons:

• It ensures the surface is stable, safe, and long-lasting.
• It supports the environment by using recycled materials where possible.
• It improves water drainage and helps reduce flooding risks in some projects.

To summarise

• There are several types of aggregate available, and each has its own purpose.
• Type 1 aggregate is strong and compactable, which is great for sub-bases.
• Type 2 aggregate offers both strength and drainage, with sustainable benefits.
• Type 3 aggregate is best for drainage-heavy projects like driveways or sports surfaces.

Looking for the right aggregate type for your project? Well, now you’ve got all the key facts, especially the differences between type 1, type 2, and type 3 aggregate, you can now make a confident choice based on strength, drainage, and sustainability.

If you have any further questions or would like to learn more about our types of aggregates, feel free to visit your local Howarth Timber branch or contact our customer service team on 01472 907051.

You can also browse our full selection of aggregates, or pop into a branch for friendly advice and support.